This invention relates to a shoe comprising a sole having a supporting surface for supporting a foot and an upper connected with the sole for locking a foot onto the supporting surface, the sole comprising an elongate torsion stiffener for enhancing resistance to torsion about the longitudinal axis of the sole.
Such a shoe is generally known and is used for protecting the foot in walking, specifically in walking over an artificially constructed, hardened flat ground.
In the known shoe, the sole is provided with an elongate torsion stiffener for enhancing resistance to torsion about the longitudinal axis of the sole. The torsion stiffener is of strip-shaped design and extends along the centerline of the sole from a part of the heel of the shoe located centrally under the heel of the foot as far as a bending line extending in use under the ball of the foot, transversely to the longitudinal axis. The torsion stiffener is so arranged that the resistance to torsion about the longitudinal axis of the sole is substantially constant along the torsion stiffener and is the same in inward and in outward direction. xe2x80x98Stiffenerxe2x80x99 is a term commonly used in the art for such provisions.
In the known shoe, the sole may be provided with a correction area of slightly raised design for correcting the position of the foot while being supported on the sole, such that at the correction area the distance between the supporting surface and a tread surface of the sole is greater. The correction area is located under the curved arched part of the inner foot, such that sagging of the arched part of the foot is prevented.
During walking, the foot rolls over the sole from the heel via the middle foot through to the toes. The sole of the shoe on which the sole is supported thereby rolls likewise from a heel part located adjacent the heel of the foot over the tread surface in the direction of the longitudinal axis of the sole, through to a tip portion of the sole, located beyond the toes.
A disadvantage of the known shoe is that both during standstill and during walking, the shoe forces the foot to assume an unfavorable position. In particular, the outer margin of the foot, during standstill, is located relatively low, and during walking the foot rolls along the outer margin. As a result, during the rolling movement of the foot, there is an increasing tendency for the foot to twist outwards. The tendency to twist outwards is present in particular during the second part of the rolling movement, i.e., during and following the rolling movement of the middle foot. To correct this unfavorable position, a human will try, both when standing still and when walking, to correct the position of the foot by means of his muscles.
Not only does such correction take a relatively large amount of energy, it also entails a relatively heavy loading of the muscles and the joints. In particular in humans who use their feet intensively, such as sportsmen, this may give rise to injuries and/or adversely affect running performance. In addition, in older people, walking may be rendered more difficult due to a lack of corrective muscular strength or due to pain in the joints owing to the unfavorable position of the foot.
The object of the invention is to provide a shoe of the type mentioned in the opening paragraph hereof, in which the above-mentioned disadvantages are avoided. To that end, the shoe according to the invention is characterized in that the torsion stiffener extends in outward direction diagonally across the sole, such that as the sole is made to roll along the longitudinal axis by the foot, the resistance to outward torsion increases. What is thereby achieved is that the outward twisting of the foot, in particular during the second part of the rolling movement, can be prevented by means of the torsion stiffener, so that during walking the muscles, as far as correction is concerned, can be further relieved, and the above-mentioned advantages can be further enhanced.
Not only can the risk of injuries in sportsmen be reduced in this way, but also the running performance can be enhanced in that more energy is made available for the forward running movement. In older people, less muscular strength is needed for walking, so that walking can be facilitated. What can moreover be achieved is that due to the foot being better supported during its rolling movement, incorrect loading of the joints is prevented, which reduces the risk of pain in the joints and wear of joints. In particular in older people, this can facilitate walking.
In an advantageous embodiment, a shoe according to the invention is characterized in that the sole is provided with a correction area of slightly raised design for correcting the position of the foot while being supported on the sole, such that at the correction area the distance between the supporting surface and the tread surface of the sole is greater, the correction area comprising a first correction subarea, located on the inner side of the sole, which corresponds with the sustentaculum tali and the navicular bone of the foot, and a second correction subarea, located on the outer side, which corresponds with the outer margin of the foot adjacent the outermost metatarsals and phalanges of the foot. What is thus achieved is that the a foot, when standing still and during walking, can be brought into a more neutral position, i.e., more into a position the foot would assume when standing still and in walking on soft ground. In particular, by means of the first correction subarea adjacent the sustentaculum tali and the navicular bone inward torsion about the longitudinal axis of the foot is prevented, while by means of the second correction subarea adjacent the outermost metatarsals and innermost phalanges adjacent the margin of the foot outward torsion about the longitudinal axis of the foot is prevented. This can prevent the occurrence of torsion of the foot relative to the longitudinal axis, so that the muscles can be further relieved not only during walking but also when standing still.
By providing the sole adjacent the supporting area of the cuneiform bone and the metatarsals on the inner side (medial side) of the foot with a lowered area where the distance between the supporting surface and the tread surface of the sole is normal, or at least reduced relative to the first correction subarea, it is accomplished that the occurrence of torsion can be further prevented, and the neutral position can be approximated more closely.
Further advantageous embodiments of the invention are set forth in the subclaims.
It is noted that in this context, xe2x80x98outwardxe2x80x99 is understood to mean the direction extending during walking in forward direction of the sole from the inner side of the foot located on the side of the foot arch to the outer side located on the opposite side at the outer margin of the foot, i.e., when oriented in the walking direction, for the right sole to the right and clockwise relative to the longitudinal axis, and for the left sole to the left and counterclockwise, respectively, while xe2x80x98inwardxe2x80x99 is to be understood to mean the obverse mutatis mutandis.